C.O.L.R. Object Editor
From Just Solve the File Format Problem
C.O.L.R. Object Editor is a graphics program for the Atari line of computers.
.mur combines with the pallete file
.pal to produce an image. Only 1 example is known. The
.mur file is 32000 bytes and the
.pal file is 96 bytes. It wouldn't be surprising if these are fixed sizes.